The most recent blogs at Green Building Advisor

Many GBAGreenBuildingAdvisor.com readers have built homes with 4 inches or 6 inches of rigid foam on the exterior side of their walls. Typically, these walls include vertical 1x4 furring strips, 16 inches or 24 inches on center, on the exterior side of the rigid foam. The furring strips perform at least three functions: they hold the foam in place, they create a rainscreenConstruction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials; most commonly produced by installing thin strapping to hold the siding away from the sheathing by a quarter-inch to three-quarters of an inch.
gap, and they provide something for the siding to be fastened to.

If you think electric vehicles are still a niche technology, think again. The International Energy Agency (IEA) estimates that more than 1 million electric vehicles (EVs) were on the road in 2015, including 400,000 in the United States. In order to limit global warming to 2 C° or less, the agency says the world will need 150 million EVs by 2030 and 1 billion by 2050, implying a 21% compound annual growth rate from now until 2050.

Earth’s atmosphere has long served as a free dump for carbon dioxide and other greenhouse gases generated by humans. That is changing as policy-makers embrace economists’ advice that the best way to cut greenhouse gas emissions is to charge an atmospheric disposal fee. As a result, governments are increasingly tacking on a price for carbon when fossil fuels are sold or consumed, allowing their economies to internalize some of the social and economic costs associated with burning coal, oil, and natural gas.

A GBAGreenBuildingAdvisor.com reader by the name of Green Heron has recommendations in hand from an HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractor for heating and cooling a Climate Zone 2 house currently undergoing renovations. But he's not sure whether the recommendations make sense.

The contractor has proposed a four-zone system using a mix of ductless and ducted minisplits, Green Heron explains in a post in GBA's Q&A Forum. A single 3-ton compressor would run the four indoor heads — two ducted units installed in the attic, and ductless units in both the kitchen and the living room.

The simplest thing to do, of course, is to get a bigger air conditioner. That crude solution certainly works: if you blast enough cold air into a building — even a leaky, poorly insulated building — you can lower the indoor air temperature. (Of course, adopting this approach is no guarantee of success, since central air conditioning systems are often poorly designed and haphazardly installed.)

Editor's note: Kent Earle and his wife, Darcie, write a blog called Blue Heron EcoHaus, documenting their journey “from urbanites to ruralites” and the construction of a superinsulated house on the Canadian prairies. The blog below was originally published in February. A complete list of Kent Earle's GBAGreenBuildingAdvisor.com blogs can be found below.

But the question I get more than any other on this topic is about whether or not the insulation on the attic floor should be removed when insulating the roof deck in an existing home. As you can tell from the title of this article, my answer is to remove it. Here are my three reasons, in increasing order of importance.

The toughest climate challenges involve large global industries, with no good substitutes. One of these literally produces the material under our feet — concrete. Every year, each of us in the U.S. uses about one-third of a ton. Fast-growing developing countries use far more. Globally we produce over 4 billion metric tons of Portland cement per year — the key ingredient in concrete and responsible for the majority of its CO2 footprint — driving over 5% of total anthropomorphic CO2.

The Colorado River’s two great reservoirs, Lake Mead and Lake Powell, are in retreat. Multi-year droughts and chronic overuse have taken their toll, to be sure, but vast quantities of water also are lost to evaporation. What if the same scorching sun that causes so much of this water loss were harnessed for electric power?

Installing floating photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. arrays, sometimes called “floatovoltaics,” on a portion of these two reservoirs in the southwestern United States could produce clean, renewable energy while shielding significant expanses of water from the hot desert sun.